This is on its way to the "At High Tide" (http://www.wmhf.org/athightide/) website. Thought you might like a sneak peek.

At High Tide will expand upon the progressive efforts first put into
practice at September Storm in 2007. Just as in the actual war,
wounded will be escorted or carried from the field of battle. Taken
to aid stations manned by medical staff, they will be given initial
treatment, and then either sent back to their units, kept until the
battle subsides or loaded into ambulances for transport to the rear
for more immediate treatment.

This procedure is documented in many sources. Here is the one
Woodward included in his "Hospital Steward's Manual":

The hospital attendants who go upon the field may be divided into two
classes: those who accompany the medical officers, who go upon the
field for the immediate succor of the wounded, and those who accompany
the ambulances and litters to help the wounded into them, or bear the
hand-stretchers.

Each medical officer should be accompanied upon the field by an
orderly, who carries the hospital knapsack, in which is placed a.
supply of instruments, dressings, &c. for immediate use. When the
surgeon stops to give his services to a wounded man, the orderly at
once un-slings his knapsack and opens it to hand out to the surgeon
the articles needed in dressing the patient. The medical officer
should also be accompanied by two intelligent attendants, one of them
a hospital steward where possible, to assist him in any operation he
may perform upon the field.

The ambulances are to be accompanied by a sufficient number of
attendants, with hand stretchers, to pick up the wounded and carry
them from positions inaccessible to the ambulances, or where it is not
advisable that these should go, to the nearest ambulances, or field
depot. In lifting the wounded and placing them. upon the stretchers,
the greatest tenderness should be used, especially where there is
reason to avoid jolting as much as possible while going to the depot.
Arrived at the depot, the ambulance is to be backed up as near the
entrance as possible, the litters, with the patients upon them, are to
be drawn out one by one, and carried to the place assigned them, the
patients removed, the litters replaced, and the ambulance starts off
once more for a fresh load.

The number of hospital attendants allowed in the field being usually
found insufficient for this purpose, an additional detail is generally
required. The musicians are usually selected; but, in addition to
these, an adequate number of temporary assistants will generally be
furnished by the commanding officer, at the request of the surgeon.
The principle endeavored to be established is that the number of men
actually on that duty should be sufficiently large to give all
reasonable assistance during the engagement, in order that there may
be no excuse fur soldiers to leave the ranks under the pretence that
they are needed to assist the wounded. Hospital attendants and
soldiers specially detailed to the ambulance corps during an
engagement should remember that their duty is strictly & military one,
and that there is no more excuse for cowardice or for disobedience of
orders in their case than there is in that of any other soldiers on
duty on the field of battle. (Woodward, p.69-73)

(ed. For the Federals, this procedure was modified in the Summer of
1862 with the institution of the Federal Ambulance Corps within the
Army of the Potomac. The ambulances and drafts of men from the
regiments were simply moved into the Ambulance Corps.)
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To implement this historical procedure, Medical Staff will register
separately from their normal units to facilitate an accurate count and
communication with the Medical Director. (use the individual form)

Most Medical Officers will portray Assistant Surgeons responsible for
the aid stations and the orderlies assigned there. Hospital Stewards
and some orderlies will assist with aid station treatment and
administrative routine. Bandsman and some musicians will be detailed
to the Medical Director for assignment to the Aid Stations and
Ambulance Corps. Additionally, each field company will supply one fit
man for the duration of the event for duties as assigned by the
Medical Director. Details on the drafts will be sent to Battalion and
Company commanders as General Orders from the respective Commanding
Generals. It is expected that the field companies will rotate the men
assigned their company allotment for this detail.

Uniform requirements are the same as found under US or CS Troops.
Equipment and field dressing requirements will be communicated
directly to the Medical Officers as totals of troops are confirmed by
registrations. Some equipment, such as field litters, will be hand
receipted to those troops detailed to use them.

Scenarios will be:

At High Tide: The Wheatfield. Cemetery Hill. The Peach Orchard. Willoughby Run.

Battle Scenarios for At High Tide

To the Seminary - The First Day

Public Scenario - 11am Saturday
This action will be occurring over a span of 2 plus hours, and will feature the various attacks and counterattacks as the Confederates forced their way along the Chambersburg Pike and Mummasburg Road. Portions of Hill’s and Ewell’s Corps strike East and South into the 1st and 11th Corps of the federal Army. Just like in the original action, the fighting will start and stop, with new troops being fed into the fight, covering a distance of 1600 plus yards.

Assault at Dusk - July 2nd

For Participants only, at Dusk on Saturday
This will replicate the Attacks on the Federal far right on the evening of July 2nd, and is closed to the public. Following the exact time line, we will recreate the chaotic scene around Evergreen Cemetery at dusk.

Longstreet Attacks - the Second Day

Public Scenario - 11am Sunday
Following the actions in the Peach Orchard and Wheatfield, this action will culminate in the counterattack of the 1st Minnesota from Cemetery Ridge. We will be replicating this action much as we will do on Saturday, featuring the assaults and counterattacks that surged through the Wheatfield and Peach Orchard, and along the slopes of Cemetery Hill.

For any Medical impression questions, please send them to John
(fieldhospital@replications.com)